Meta-phenylenediamines, process for preparation thereof, intermediate compounds and use of these meta-phenylenediamines as couplers for the oxidation dyeing of keratinous fibres and especially human hair

Abstract

Compounds of formula: <IMAGE> in which R1 and R2 independently of each other denote a hydrogen atom, a C1-C4 alkyl radical or a C2-C3 mono- or polyhydroxyalkyl radical, Z and Z' independently of each other denote a C1-C4 alkyl or C2-C4 hydroxyalkyl radical, provided that when R1 and R2 simultaneously denote a hydrogen atom, Z and Z' do not simultaneously denote the methyl radical, and their addition salts with an acid, process for their preparation and their use as couplers in an aqueous carrier, in combination with at least one precursor of a para-type oxidation dye for dyeing human hair. <??>The invention also relates to the intermediate compounds of formula <IMAGE> in which R' denotes a hydrogen atom, a C1-C4 alkyl radical, a C2 or C3 mono- or polyhydroxyalkyl, acetyl or chloroethoxycarbonyl radical and Z and Z' independently of each other denote a C1-C4 alkyl radical.

We claim: 
     
       1. A compound of formula (I) ##STR23## in which: R 1  and R 2  denote, independently of one another, a hydrogen atom, an alkyl radical having from 1 to 4 carbon atoms or a mono- or polyhydroxyalkyl radical having 2 or 3 carbon atoms; and Z and Z' denotes, independently of one another, an alkyl radical having from 1 to 4 carbon atoms or a hydroxyalkyl radical having from 2 to 4 carbon atoms with the proviso that, when R 1  and R 2  simultaneously denote a hydrogen atom, Z and Z' do not simultaneously denote a methyl radical, and their addition salts with an acid.   
     
     
       2. A compound according to claim 1, which is chosen from the group consisting of 4-(β-hydroxyethyl)amino-2-amino 1,3-dimethoxybenzene, 4-amino-2-(βhydroxyethyl)amino-1,3-dimethoxybenzene, 4-methylamino-2-amino-1,3-dimethoxybenzene, 2,4-bis(β-hydroxyethyl)amino-1,3-dimethoxybenzene, 2,4-diamino-1,3-diethoxybenzene, 2,4-diamino-1,3-bis(β-hydroxypropoxy)benzene, and their addition salts with an acid.